The achievement gap, or opportunity gap, in education is when one group of students outperforms another group of students in statistical category. For decades, these gaps been analyzed in an attempt to support students and close these differences in categorical scores. The primary purpose of this dissertation was to focus on closing the achievement gap on state mathematics assessment scores in order to increase overall mathematics proficiency levels. The implementation of different interventions in the classroom and around planning for student learning was the main strategy used to improve mathematics standardized test scores, specifically with traditionally underachieving subgroups. The main instrument used to determine growth and success of the intervention models was the Smarter Balanced Mathematics Assessment (SBAC), given yearly by the state of Delaware. The growth goal was in reference to overall proficiency levels, with an increase goal of 10% building wide. Ongoing assessments and data collection throughout the year of grades, attendance, Interim Assessment Blocks (IABs), and Common Formative Assessments (CFAs), were used to assess the need for interventions and the efficacy of these interventions. Ultimately, with COVID shutdowns, cancellations of state testing, and remote/hybrid learning, the goal of increasing the overall proficiency levels by 10% did not happen. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]